AjaxMap.js browser dependant bug

I'm playing a little but with SharpMap 0.9 and I've found a subtle bug that is related to IE (IE7 in my tests).
The error is in SharpMapGetCallbackResponse and the main evidence is that sometimes, when zooming, the control remains blocked and not responds to user input; I've take a look at the code, and the cause is that, in the SharpMapGetCallbackResponse, method
the onload event sometimes it's not called by IE.
As example, this code sometimes is not performed:
imgdnew.onload = function()
{
obj.mapReady = 1; // !!!
imgdnew.onload = '';
if (obj.zoomEnded == 1)
SharpMap_BeginFade(obj);
}
this means that the controller is never restored to the mapReady status, and is unable to respond to user input.
This event is properly called by Firefox, so in this browser the error is not verified.